1. Field of the Invention
The present invention relates to a method of sensing gravity and more particularly, to a method of and apparatus for sensing gravity using an NADH oxidase of the plasma membrane.
2. Background of the Invention
Gravity determination and methods of measuring gravity are well known in the art. However, currently there are no biological gravity sensors available. Thus far, modern gravitational studies in plants have focused on molecular approaches with emphasis on genetic analyses in Arabadopsis (Fukaki H., Fujisawa H., and Tasaka M., The RHG gene is involved in root and hypocoytl gravi-tropism in Arabadopsis thaliana, 38 Plant Cell Physiol 804-810 (1997). While the identification of the Arabadopsis genes involved in gravi-perception and response will be helpful to understand root and shoot gravitropism, there is still no indication of what protein or proteins might be involved, and thus no previous disclosure or suggestion of a useful protein which would be helpful in biological gravitational sensing.
Gravity response is, of course, not limited to plants. A number of development and growth responses (axis formation and establishment of polarity in amphibia and birds, for example) are know to respond to gravitational stimuli. (McLaren A., Development Biology and Microgravity, In: L. G. Griarty. Biology in Microgravity, European Space Agency, Paris pp. 239-242, (1989). Behavior of cultured mammalian cells also has been shown to respond to microgravity with most of the responses involving cell proliferation and the production and/or response to mitogenic stimuli and growth factors. Gmunder F. K., Cognoli A., Cultivation of Single Cells in Space, 3 Appl. Microgravity Tech., 115-122, (1988). However, these previous findings have also not resulted in the development of any system which would be useful in developing an effective biological gravity sensor.
A biological gravity sensor encompassing a protein that responds to changes in gravity could have wide-spread application in space exploration and medical applications. In addition, a protein gravity sensor could be used in applications requiring a miniaturized sensor.
It is therefore an object of the invention to provide a method of biologically sensing gravity.
It is a further object of the invention to provide a simple and effective miniaturized gravity sensor.
A further object of the invention is to provide a method of sensing responses to micro-gravity in living organisms.
It has been found that the NADH oxidase protein, preferably from the plasma membrane, exhibits a response to unit gravity and low centrifugal g forces. Specific protein sources include but are not limited to intact soybean hypocotyl sections, isolated vesicles of plasma membranes from soybean hypocotyl sections and from HeLa cells (cultured human cervical carcinoma).
Accordingly, there is provided a method of sensing gravity utilizing the NADH oxidase protein. An apparatus incorporating this method is also disclosed. The method comprises delivering external NADH to the NADH oxidase, measuring the rate of NADH oxidation by the protein, and translating the rate of oxidation to represent the relative gravitational force exerted on the protein. An apparatus incorporating this method is also disclosed.
Further features and advantages of the present invention will be set forth in, or apparent from, the detailed description of preferred embodiments thereof which follows.